IDK about this, my theory is its from white lies about success. I mean look at white people and their kids now. Most of them act like their kid went out on their own and did everything and the kids act like that too. But when you really look into it, they left at 18 in the car their parents bought/pay for. Went to college that their parents or grandparents pay for, get a house or apartment their parents pay for and usually get a good paying job that their parents lined up for them & turn around telling people how they did it all on their own through hard work.
AA's really believed their lies, so now they think their 18 year olds are grown, should have it all figured out and be out on their own like they were or how they see other "successful" kids doing it. No other culture in the world has this mindset. They all stick together & move as a unit to ensure they're all secure and not struggling.
I've seen people try an justify it by saying they need to know the struggle and it makes them stronger years down the line, blah blah blah. Well congrats, your kid survived the struggled, built a bunch of character, and those "weaker" kids that had a bunch of family support are way further ahead in life/financially and are your kids bosses.
I mean, if we being real, you dont really start figuring life out till your mid 20's. So if you kid has no idea what to do in their late teens/ early 20's, my question is what have you been doing and what are you going to do to help? If you're solution is to throw them out, i see why they're lost.